A role of the difference in bed elevations in the main-river (ΔzMR) at its entrance to a 90º straight-channels' confluence is studied numerically using a 3D finite-volume model. Three characteristic hydrological scenarios with DR = {0.250, 0.583, 0.750} are analysed in four confluence layouts having ΔzMR / hd [0.0, 0.50] (where hd stands for the flow depth in the deeper canal at the confluence). It is found that: 1) a portion of the tribu-tary flow in the bottom layers is entrained by the bed-step, 2) the w- velocity has the same order of magnitude as Vxy for ΔzMR ≥ 0.25hd and DR > 0.5, 3) the opposite bank is endangered by erosion due to strong upward motion along this bank, 4) additional shear layer develops on the outer side of the distorted umax-core and 5) the presence of bed-step favours bed-load transport both in and far downstream of the confluence.
Keywords:
river confluence / bed elevation discordance in the main river / flow angles δ and φ / size of the recirculation zone / shear layer / bed shear stress distribution
Source:
River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014, 2014, 997-1005
TY - CONF
AU - Đorđević, Dejana
PY - 2014
UR - http://grafar.grf.bg.ac.rs/handle/123456789/1858
AB - A role of the difference in bed elevations in the main-river (ΔzMR) at its entrance to a 90º straight-channels' confluence is studied numerically using a 3D finite-volume model. Three characteristic hydrological scenarios with DR = {0.250, 0.583, 0.750} are analysed in four confluence layouts having ΔzMR / hd [0.0, 0.50] (where hd stands for the flow depth in the deeper canal at the confluence). It is found that: 1) a portion of the tribu-tary flow in the bottom layers is entrained by the bed-step, 2) the w- velocity has the same order of magnitude as Vxy for ΔzMR ≥ 0.25hd and DR > 0.5, 3) the opposite bank is endangered by erosion due to strong upward motion along this bank, 4) additional shear layer develops on the outer side of the distorted umax-core and 5) the presence of bed-step favours bed-load transport both in and far downstream of the confluence.
PB - CRC Press, Taylor & Francis Group
C3 - River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014
T1 - Effect of bed elevation discordance in the main river on the confluence hydrodynamics in 90o straight-channels’ confluences
EP - 1005
SP - 997
DO - 10.1201/b17133
ER -
@conference{
author = "Đorđević, Dejana",
year = "2014",
url = "http://grafar.grf.bg.ac.rs/handle/123456789/1858",
abstract = "A role of the difference in bed elevations in the main-river (ΔzMR) at its entrance to a 90º straight-channels' confluence is studied numerically using a 3D finite-volume model. Three characteristic hydrological scenarios with DR = {0.250, 0.583, 0.750} are analysed in four confluence layouts having ΔzMR / hd [0.0, 0.50] (where hd stands for the flow depth in the deeper canal at the confluence). It is found that: 1) a portion of the tribu-tary flow in the bottom layers is entrained by the bed-step, 2) the w- velocity has the same order of magnitude as Vxy for ΔzMR ≥ 0.25hd and DR > 0.5, 3) the opposite bank is endangered by erosion due to strong upward motion along this bank, 4) additional shear layer develops on the outer side of the distorted umax-core and 5) the presence of bed-step favours bed-load transport both in and far downstream of the confluence.",
publisher = "CRC Press, Taylor & Francis Group",
journal = "River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014",
title = "Effect of bed elevation discordance in the main river on the confluence hydrodynamics in 90o straight-channels’ confluences",
pages = "1005-997",
doi = "10.1201/b17133"
}
Đorđević, D. (2014). Effect of bed elevation discordance in the main river on the confluence hydrodynamics in 90o straight-channels’ confluences.
River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014
CRC Press, Taylor & Francis Group., 997-1005.
https://doi.org/10.1201/b17133
Đorđević D. Effect of bed elevation discordance in the main river on the confluence hydrodynamics in 90o straight-channels’ confluences. River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014. 2014;:997-1005
Đorđević Dejana, "Effect of bed elevation discordance in the main river on the confluence hydrodynamics in 90o straight-channels’ confluences" River Flow 2014, Proceedings of the International Conference on Fluvial Hydraulics, Lausanne, Switzerland, 3-5 September 2014 (2014):997-1005,
https://doi.org/10.1201/b17133 .
,